Technical Field
The present invention relates to a laryngeal mask.
Background Art
Laryngeal masks for securing an airway in the human body while blocking communication between the esophagus and the trachea are known in the prior art. An explanation is first provided of the structure of the human body J with reference to FIG. 6.
The human body J has a nasal cavity J1, an oral cavity J2, a pharyngeal portion T communicated with the nasal cavity J1 and the oral cavity J2, and an esophagus J5 and a trachea J6 branching from this pharyngeal portion T. A first constricting portion J4, which is constricted by the action of a sphincter for establishing or blocking communication between the esophagus J5 and the pharyngeal portion T, is formed on the upstream side of the esophagus J5.
For example, a laryngeal mask described in Japanese Unexamined Patent Publication No. 2003-511108 is provided with an airway tube inserted into the body through the oral cavity J2, and a masking ring provided on the leading end of this airway tube. The masking ring has an elliptical shape and can be inflated and deflated. The leading end of the airway tube opens into an interior region of the masking ring, and an artificial respirator can be connected to the base end of the airway tube.
In the case of using the laryngeal mask of Japanese Unexamined Patent Publication No. 2003-511108, the airway tube is inserted into the body until the leading end of the deflated masking ring contacts the region of the sphincter (namely, the first constricting portion J4). In other words, a medical professional discontinues insertion of the laryngeal mask when a sensation is felt of the leading end of the masking ring having contacted the region of the sphincter. While in this state, the masking ring adheres tightly to the opening of the trachea J6 as a result of being inflated. As a result, communication between the esophagus J5 and the trachea J6 is blocked. In addition, while in this state, the trachea J6 is able to communicate with an artificial respirator through the airway tube that opens into the interior region of the masking ring. Thus, an airway can be secured while blocking communication between the esophagus J5 and the trachea J6.
However, in the case of using the laryngeal mask described in Japanese Unexamined Patent Publication No. 2003-511108, it is difficult to accurately secure an airway.
More specifically, the depth at which the laryngeal mask described in Japanese Unexamined Patent Publication No. 2003-511108 is inserted into the body is determined based on the presence or absence of the sensation felt when the leading end of the masking ring contacts the region of the sphincter (namely, the first constricting portion J4). Here, the region of the sphincter (the first constricting portion J4) is soft tissue and easily deformed. Consequently, it is difficult to accurately determine whether the masking ring has contacted the first constricting portion J4. Moreover, if the insertion site of the masking ring shifts from the target opening of the trachea J6, an airway cannot be accurately secured even if this masking ring is inflated.